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AR-5 ?


owlsplace

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I was dropping off some items at the thrift store the other day and noticed a pair of AR-5s sitting on the tarmac so I went back the next day to see what they looked like and ended up buying them for a song, literally.

I bought a pair when I was in Germany back in the mid-70s which had oiled-walnut cabinets and dark grill cloths. The thrift shop pair have Formica laminate finish and light colored grill cloth. I wasn't aware that AR used Formica.

Anyway, these speakers sound great to my aging ears minus one woofer surround which will soon be remedied. They could use some new grill cloth and one badge was missing.

How likely is it that the crossover caps need to be replaced?

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Nice score.

If the surround foam is gone I wouldn't play them. You can cause damage.

I would change the capacitors unless they are Sprauge; but even then I'd check them. The AR5 was made 1968 to 1976 so the caps are quite old.

Here's a link to a nice xover wiring schematic> http://www.classicspeakerpages.net/library/acoustic_research/original_models_1954-1974/original_models_schematicss/ar-5_schematic.pdf

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This looks like your first post, so welcome to CSP.

Very nice speaker, that AR-5, yep, it is indeed. For future posts, be aware that you will normally receive far more detailed advice if you have posted pics of your speaker situation.

But w/o pics to advise more specifically, I would just suggest that maybe you consider replacing both woofer foams at the same time; maybe consider replacing some or all capacitors; and definitely consider restoring or replacing all midrange and tweeter controls.

Have never seen any AR speakers with Formica (altho' it certainly could have been applied later, beyond the factory), but some later "classic" models were sent to market with the cheesy vinyl simulated walnut, which just might be what you are observing. Still, I thought all AR-5's were supplied with real wood veneer, but that statement may not be fully correct. Pics would indeed help.

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Yes, that was my first post, thanks for the greeting and same back to all. I'll see what I can do on pics.

The AR-5s were set up for bi-amping so you can drive them with the woofer out.

The pots, much to my surprise appear to be fully functional. I haven't looked at the crossovers yet as playing around in fiberglass is not one of my favorite pastimes. Thought I would get some feedback on the condition of the caps before digging into the cabinets. Besides I've been having fun listening to them again. Lot's of old memories there.

This model seems to be somewhat rare compared to ARs other offerings so I would like to keep them original although the Formica is rather unusual it seems and may not be original. I've read various explanations as to why the 5s didn't sell very well. To me the missing 1/3rd octave of bass response was geared more towards apartment dwellers. They didn't want to attract the attention of their neighbors while listening to their favorite tunes at normal volume levels while still being able to enjoy the best sound AR had to offer.

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Yes, that was my first post, thanks for the greeting and same back to all. I'll see what I can do on pics.

The AR-5s were set up for bi-amping so you can drive them with the woofer out.

The pots, much to my surprise appear to be fully functional. I haven't looked at the crossovers yet as playing around in fiberglass is not one of my favorite pastimes. Thought I would get some feedback on the condition of the caps before digging into the cabinets. Besides I've been having fun listening to them again. Lot's of old memories there.

This model seems to be somewhat rare compared to ARs other offerings so I would like to keep them original although the Formica is rather unusual it seems and may not be original. I've read various explanations as to why the 5s didn't sell very well. To me the missing 1/3rd octave of bass response was geared more towards apartment dwellers. They didn't want to attract the attention of their neighbors while listening to their favorite tunes at normal volume levels while still being able to enjoy the best sound AR had to offer.

Most AR models of that era had separate woofer and high range + input terminals and a common - terminal, but this was not meant for bi-amping...more for adding outboard tweeters.

The caps may have drifted out of spec, but it is very rare for them to stop functioning. You won't know anything for sure unless you measure them. Some caps used by AR were better than others, but you will not get useful feedback until you examine them or post a photo of them.

Your priority should be the woofer foam.

Roy

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Should have the woofers back in spec by the weekend with any luck.

You're right on the bi-amping, would need to add another input post to bypass the low-range crossover components. I don't have any need for that level of performance these days at any rate although I did pair some 15" dbx woofers with Ohm speakers a few years back -- no one in the neighborhood appreciated the spectacle :blink:

Also, it looks like the inputs are mislabeled on the wiring schematic referenced above.

Roger

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Also, it looks like the inputs are mislabeled on the wiring schematic referenced above.

Roger

The inputs are properly labeled. I'm guessing you are referring to the caps being located on the negative side of the circuit. It was an AR thing. :)

Roy

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The inputs are properly labeled. I'm guessing you are referring to the caps being located on the negative side of the circuit. It was an AR thing. :)

Roy

No, I was referring to the #10 coil should be connected to the #2 post.

Roger

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No, I was referring to the #10 coil should be connected to the #2 post.

Roger

Oh yeah...nice catch, Roger...and the yellow wires should be connected to "T". Carl's going to have to issue a recall on this one. :) Since then we've also learned that the resistor is supposed to be 1.5 ohms not 1.35 ohms, and earlier AR-5's will have #6 and #8 coils instead of #10 and #11 coils.

Attached is an "official" AR-5 schematic. Not as pretty, but more accurate.

Roy

AR-5 schematic (from AR).pdf

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This is the version of the AR-5 schematic that I happen to find easy to read, even though it still shows the mid resistor at 1.3 ohms.

Hi Robert,

That is actually one I drew a long time ago using a 3a schematic drawn by John O'Hanlon when we were working on the AR-3a restoration guide. The nichrome resistor wire value was originally based on a couple of my measurements (which I shared as "1.3+ ohms" with Carl), but was later shown to be 1.5 ohms in the previously unavailable original AR schematic posted above.

I just updated it to show the proper resistor value (see below).

Roy

post-101150-0-79739000-1407298233_thumb.

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Hi Robert,

That is actually one I drew a long time ago using a 3a schematic drawn by John O'Hanlon when we were working on the AR-3a restoration guide. The nichrome resistor wire value was originally based on a couple of my measurements (which I shared as "1.3+ ohms" with Carl), but was later shown to be 1.5 ohms in the previously unavailable original AR schematic posted above.

I just updated it to show the proper resistor value (see below).

Roy

Looks good, Roy.

My original AR-5s were powered by a Pioneer SA-9100 amp with a Soundcraftsman 10-band stereo equalizer in the loop. The set was rounded out with a Thorens 160C turntable with Shure V15 type III cartridge, Tandberg 9200xd, Teac A450 and the matching Pioneer tuner. I was tempted to add a Dynaco 400 amp but never got around to it. Those days were simple times with simple pleasures :rolleyes:

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Thanks for the updated drawing, Roy, it is a great little diagram. Trying not to get overly excited about a crossover drawing, but this is exactly what a x-o schematic should communicate - - - simplicity, brevity and clarity. I do really like those original AR documents (as shown in post #9), but this is a notable improvement over that - - - no line work crosses over other lines, discrete use of color confirms original factory wiring, polarity is crystal clear, and each driver circuit is easily identified at-a-glance with its associated components.

Roger, that original set-up of yours has some terrific pieces of 40 year-old gear. Keep us updated on your project, and post some pics if possible - - - if you need assistance with how-to-post-pics, just ask. JPEG files are best, IMO, and no need to be larger than 100 KB digital files.

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Well, here is a fairly good overview of what the AR-5s with Formica finish look like.

Has anyone attempted to put together a serial number database?

These are consecutively numbered in the low 24,000 range.

Roger

post-173498-0-73159900-1407350603_thumb.

post-173498-0-00128800-1407350612_thumb.

post-173498-0-70700400-1407350619_thumb.

post-173498-0-71219700-1407350630_thumb.

post-173498-0-20586500-1407350638_thumb.

post-173498-0-97943000-1407350644_thumb.

post-173498-0-89594500-1407350651_thumb.

post-173498-0-58264500-1407350658_thumb.

post-173498-0-50156200-1407350670_thumb.

post-173498-0-61285500-1407350679_thumb.

post-173498-0-65138400-1407350688_thumb.

post-173498-0-61081800-1407350697_thumb.

post-173498-0-56887200-1407351604_thumb.

post-173498-0-80740800-1407351614_thumb.

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The drivers appear to be in great shape, Roger! The woofer surrounds are original and unusually intact.

The cabinets are the "unfinished pine" version to which someone glued formica. It is not original to the cabinets.

Looking forward to a photo of the crossover.

Roy

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(edited) Ok, here are the crossover components with a few measurements:

Nichrome wire resistor measured 1.51 ohms in circuit.

The 4µF cap measured 34.3µF with the woofer out of the circuit and the bridge link disconnected.

The unsoldered double cap measurements are: blue to green = 30.6µF; blue to black = 97.7µF -- should read 24 and 72 respectively.

Obviously some issues with the caps.

No markings were visible on any of the caps.

Roger

post-173498-0-55491300-1407361106_thumb.

post-173498-0-35757900-1407361115_thumb.

post-173498-0-84812900-1407361124_thumb.

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Ok, here are the crossover components with a few measurements:

Nichrome wire resistor measured 1.51 ohms in circuit.

The 72 mfd cap measured 34.3 mfd with the woofer out of the circuit and the bridge link disconnected.

The unsoldered double cap measurements are: blue to green = 30.6 mfd; blue to black = 97.7 mfd -- should read 24 and 4 respectively.

Obviously some issues with the caps.

No markings were visible on any of the caps.

Roger

That huge double cap should be 24uf (blue to green) and 72uf (blue to black), so both parts have drifted upward. The 4 uf cap is the round one in the upper right corner above the #10 coil. These were very reliable caps, but should be replaced at this point.

At least nobody has tampered with them, which was another reason I wanted to see the crossover.

Thanks for the photos!

Roy

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That huge double cap should be 24uf (blue to green) and 72uf (blue to black), so both parts have drifted upward. The 4 uf cap is the round one in the upper right corner above the #10 coil. These were very reliable caps, but should be replaced at this point.

At least nobody has tampered with them, which was another reason I wanted to see the crossover.

Thanks for the photos!

Roy

You're welcome, Roy, I was curious to find out their condition myself. On further inspection I pulled the double cap out of the cabinet and remeasured just to make sure. The round cap now measures 4.1µF which is where it is supposed to be.

Do I need to leave the double cap in the box to avoid changing the resonance? Or can I leave it out? It takes up quite a bit of space.

Will be hunting up some caps -- any suggestions?

I cleaned off the degraded foam from the double capacitor to reveal the manufacturers markings. The 908 mark -- possibly a date code for September 1968?

Meanwhile, I brought the Ohms downstairs to replace the ARs. I haven't listened to music for quite awhile and I decided I miss it after testing the ARs. I'm sure the Ohms need work also but taking those cans apart looks daunting. I am finding this whole event rather rejuvenating :) I've obviously been suppressing this part of my character for a long time.

Roger

post-173498-0-42096000-1407377977_thumb.

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You're welcome, Roy, I was curious to find out myself. On further inspection I pulled the double cap out of the box and remeasured just to make sure. The round cap now measures 4.1µF which is where it is supposed to be.

Do I need to leave the double cap in the box to avoid changing the resonance? Or can I leave it out?

Will be hunting up some caps -- any suggestions?

I cleaned off the degraded foam from the double capacitor to reveal the manufacturers markings. The 908 mark -- possibly a date code for September 1968?

Roger

I also have found that 4uf cap to consistently measure well.

Based on cabinet serial numbers, your 5's were probably manufactured in 1971. Dates can often be found stamped on the driver magnets. I don't know the date codes for the big block caps.

I wouldn't worry about removing the big caps....and it will give you more room for the replacements.

Popular film cap choices are Parts Express' Dayton, Erse polyester (mylar), Carli mylar, Madisound "surplus" film caps. Some people advocate using electrolytic caps because they are inexpensive and ESR may be closer to that of the original caps. I don't buy into capacitor marketing hype or "audiophile" conjecture, so I mostly use Erse polyester and bundled Madisound surplus (10uf) caps. I do not use anything more expensive than Daytons (5% variety), which are excellent.

Roy

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...

Popular film cap choices are Parts Express' Dayton, Erse polyester (mylar), Carli mylar, Madisound "surplus" film caps. Some people advocate using electrolytic caps because they are inexpensive and ESR may be closer to that of the original caps. I don't buy into capacitor marketing hype or "audiophile" conjecture, so I mostly use Erse polyester and bundled Madisound surplus (10uf) caps. I do not use anything more expensive than Daytons (5% variety), which are excellent....

I'm not finding any 72µF caps, are 68µF suitable replacements? Add a 4µF with it?

Roger

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Sure, you can bundle them.

The original caps had a 10% tolerance. Typical "5%" film caps usually measure pretty much on the money, so you do not have to use the precise value, especially the large ones. The AR-5 cap "kit" sold on Ebay by Vintage AR is comprised of Dayton 4uf, 25uf, and 75uf polys, and works very well.

Roy.

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I also have found that 4uf cap to consistently measure well.

Based on cabinet serial numbers, your 5's were probably manufactured in 1971. Dates can often be found stamped on the driver magnets. I don't know the date codes for the big block caps.

I wouldn't worry about removing the big caps....and it will give you more room for the replacements.

Popular film cap choices are Parts Express' Dayton, Erse polyester (mylar), Carli mylar, Madisound "surplus" film caps. Some people advocate using electrolytic caps because they are inexpensive and ESR may be closer to that of the original caps. I don't buy into capacitor marketing hype or "audiophile" conjecture, so I mostly use Erse polyester and bundled Madisound surplus (10uf) caps. I do not use anything more expensive than Daytons (5% variety), which are excellent.

Roy

I was wondering about all the cap-hype -- it gets pricey fast. If you can't actually verify any difference in response via a listening test you would have more fun buying music instead.

I think I will gut the original double cap and install the replacements inside to maintain the original cabinet volume.

Thanks for the date estimate... that was the year I graduated from high school and three years before I bought my first pair of AR5s.

Roger

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I was wondering about all the cap-hype -- it gets pricey fast. If you can't actually verify any difference in response via a listening test you would have more fun buying music instead.

I think I will gut the original double cap and install the replacements inside to maintain the original cabinet volume.

Thanks for the date estimate... that was the year I graduated from high school and three years before I bought my first pair of AR5s.

Roger

The caps do not represent enough volume to be a cabinet resonance issue. As time went on AR used much smaller caps in the AR-5 as well all other models. If anything at all, you may lower fc by a tiny fraction...which is not a bad thing. When we were working on the AR-3a restoration document (in this forum's Library) we conducted many measurements relative to stuffing type and amount, with and without crossover caps present. The caps were of no significance to the bigger picture. There are more important things to expend energy on. For example, be sure to keep the fiberglass stuffing you remove from each cabinet in separate bags and keep the bags with the cabinets. Stuffing amounts are pertinent to your resonance concerns.

You should also open and clean the level controls. They will become a problem even if they seem OK now.

Take a look at the 3a restoration document in this forum's Library. The 3a and 5 are very similar, and many issues pertinent to all early AR models are discussed there.

Roy

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If you can't actually verify any difference in response via a listening test you would have more fun buying music instead.

AMEN to that!

You obviously know what you're talking about and any questions are/will be expertly answered by Roy, but I can't resist throwing in 2 cents worth ;) :

For your 2 speakers, a good value would be 18 of these: http://www.madisoundspeakerstore.com/surplus-capacitors/10.0-mfd-polypropylene-cap-10mfdp/tyee/

You can bundle 7 to make 70uF. No need to add another 2uf but if you do these are OK but have only 1/2" leads: http://www.madisoundspeakerstore.com/surplus-capacitors/2.0mfd/

These are easier to work with: http://www.madisoundspeakerstore.com/carli-capacitors/carli-mylar-2.2mfd-150v/

For the 4uF and to add to your 24uF bundle, these are good: http://www.madisoundspeakerstore.com/carli-capacitors/carli-mylar-3.9-mfd/

You could also go with electrolytics for the big caps. This: http://www.madisoundspeakerstore.com/electrolytic-cap-100vdc/bennic-50-mfd-electrolytic-caps/

plus this: http://www.madisoundspeakerstore.com/electrolytic-cap-100vdc/bennic-22-mfd-electrolytic-caps/

Or, if you don't want to bundle seven 10uF caps you could use this: http://www.madisoundspeakerstore.com/solen-capacitors/solen-70-mfd-fast-cap-400v/

Great find and a worthy restoration.

Kent

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